Dispersion mills



April 19, 1955 T. J. LAIRD DISPERSION MILLS 2 Sheets-Sheet 1 Filed April 2, 1952 A TTORNEYS April 9, 1955 T. J. LAIRD 2,706,621

DISPERSION MILLS Filed April 2, 1952 2 Sheets-Sheet 2 42F .1. 20 {k T Q AK \L g L{ L jlli i0 5 22 IN V EN TOR.

THOMAS J. LAIRD ATTORNEYS United States Patent 7' DISPERSION MILLS Thomas J. Laird, Buffalo, N. Y., assignor to Kinetic Dispersion Corporation, Buffalo, N. Y.

Application April 2, 1952, Serial No. 280,067

2 Claims. (Cl. 259-96) This invention relates to dispersion mills and more particularly to apparatus for producing suspensions of finely divided solids in liquids.

The present apparatus relates generally to the mixing art but deals more particularly with special and especially difficult dispersion problems which are encountered in producing dispersions of paint pigments, printing inks, lacquers, carbon paper coatings, and the like in solvents or vehicles of various kinds. Heretofore the production of dispersions of this kind have been possible only by long drawn out processes usually involving the successive employment of a series of steps requiring separately designed and constructed mixing and blending apparatuses and, of course, requiring the transfer of batches of material from each piece of apparatus to the next.

The problem of thoroughly dispersing pigments or other solid highly discrete materials in vehicles and. solvents in the manufacture of paint, printing inks, lacquers, enamels, varnishes, carbon paper coatings and similar materials is a difficult and vexatious one and the time required for dispersion as well as the degree of dispersion attained within given limits are highly important factors both in the quality of the ultimate product and in the total cost of production. The general problem is accentuated by the fact that the pigments and other solid and semi-solid materials to be dispersed are frequently very tenacious or viscous and very complete dispersions of the materials are required.

Further, the percentage composition of the discrete solid or semi-solid material is often very high in the products prepared with the present apparatus as compared with ordinary mixing problems. Often the vehicles themselves are quite viscous, which further complicates the problem of achieving a thorough Wetting and dispersion within practical and economical limits.

The present apparatus thoroughly disperses compositions and mixtures of the general class referred to above in a surprisingly thorough manner and in a much shorter time than that required in dispersion mills of the prior art operating upon similar compositions.

A complete and specific embodiment of the invention is illustrated in the accompanying drawings and described in detail in the following specification. However, it is to be understood that this embodiment is set forth by way of example only, and that the invention is not limited excepting as defined in the appended claims.

The present application is a continuation-in-part of my copending application Serial No. 59,486 filed November 12, 1948 now Patent No. 2,628,081 granted Feb. 10, 1953.

In the drawings:

Fig. 1 is a general elevational view of one form of the dispersion apparatus of the present invention;

Fig. 2 is a fragmentary horizontal cross sectional view taken approximately on the line Il-II of Fig. l but on a considerably larger scale; and

Fig. 3 is a cross sectional view taken approximately on the line III-III of Fig. 2.

Throughout the several figures of the drawings like characters of reference denote like parts and, referring particularly to Fig. 1, the numeral designates generally a round bottomed vessel which provides a charge receiving chamber. In the present instance a spaced outer wall 11 provides a jacket for receiving a heat exchanging liquid medium. A removable double walled cover member for the vessel is indicated generally at 2,706,521 Patented Apr. 19, 1955 12 in Fig. 1. The dispersion means which forms the subject matter of the present invention is designated generally 13 in Fig. 1 and is shown in greater detail in Figs. 2 and 3. Referring particularly to Fig. 3, a rotor shaft 14 is supported for anti-friction bearing rotation in a bearing 15 which includes means sealing the same and the rotor shaft against outward fiuid flow and which need not be further described, insofar as the present invention is concerned. Bearing 15 is welded into an annular flange or ring member 16 which seats centrally against the bottom portion of vessel 10 and a spacing ring 17 is welded centrally between the vessel 10 and the outer jacket wall 11. A circular series of screws 18 secures ring member 16 and bearing 15 to the rigid assembly comprising vessel 10, jacket wall 11 and spacing ring 17 as clearly shown in Fig. 3.

The dispersion members per se comprise a series of three annular members, upper and lower annular plates 20 and 21 and an intermediate stator ring 22. The three members 20, 21 and 22 are assembled as a rigid unit by a circular series of screws 24 and the whole is supported in position substantially above the bottom of vessel 10, by a circular series of studs 25 whose lower ends are threaded into ring member 16 and whose upper ends are threaded into the lower annular plate 21, the studs 25 being staggered with respect to the series of screws 24. Spacing sleeves 26 cooperate with i tuds3 25 to support the dispersion unit as shown in The upper and lower plates 20 and 21 are provided with tapered central openings 28 and 29 which provide entrance passages to a circular rotor chamber which is formed by the plates 20 and 21 and stator ring 22. The facing surfaces of plates 20 and 21 are provided with beveled projections 30 and 31, respectively, which have square outer shoulders which fit within the stator ring 22 as shown in Fig. 2 to define an outwardly tapering rotor chamber.

A rotor or impeller designated generally 33 is keyed to rotor shaft 14 as at 34 and may be assembled thereon by means of a nut 35 threaded on the end of rotor shaft 14. In the form shown in Fig. 3 the rotor 33 is formed in abutting upper and lower halves 40 and 41 having central hub portions 42 and 43, respectively. The abutting faces of the rotor halves include flat radially disposed portions 45 and 46 upon which are formed series of rotor blades 47 and 48, respectively. The rotor blades 47 and 48 extend outwardly of the fiat portions 45 and 46 and terminate outwardly in flat surfaces which substantially meet the beveled projections 30 and 31, as clearly shown in Fig. 3.

The rotor blades 47 and 48 are preferably curved as viewed in an axial direction as shown in Fig. 2 and terminate radially outwardly in arcuate end portions which substantially meet the inner periphery of stator ring 22, also as shown in Fig. 2. With the blades disposed as shown in the drawing the direction of rotation would be clockwise as viewed in Fig. 2.

The stator ring 22 is provided with a series of vertical radially extending slots 49. As will be noted from Fig. 2, the slots are relatively narrow and material is impinged against the inner or entrance ends of the slots and channeled outwardly through the slots at very high speed, the speed of the rotor being of the general order of ten to fifteen thousand revolutions per minute.

The rotor shaft extends downwardly and is there connected for driving engagement with a driving motor 50 by means of pulleys 50 and 51 and a driving belt 52 or in any other desired manner.

The speed of operation of the rotor is vastly greater than is usual in the paint mixing field, for instance. While the rotor speed varies somewhat depending on the formulation of the mix batch and also depending on various design factors and variable proportions in the dispersion means, peripheral rotor speeds of between 7500 and 11,000 feet have been usefully and satisfactorily employed in various dispersion applications.

I claim:

1. Dispersion apparatus comprising a vessel and dispersion means therein comprising a stator and a rotor disposed therein having outwardly projecting blades, said dispersion means including upper and lower discoidal portions disposed adjacent to the upper and lower portions of the rotor blades and including a central opening for ingress of material to be dispersed, said stator having an annular portion extending vertically between the upper and lower discoidal portions and disposed about the rotor, said rotor blades being disposed to trail relative to the direction of rotation and proportioned to terminate in relatively close juxtaposition to the inner periphery of the annular portion of the stator, said annular portion having a circumferential series of substantially radially extending passages of relatively narrow cross-section as compared with their outward extent.

2. Dispersion apparatus comprising a vessel and dispersion means therein comprising a stator and a rotor disposed therein, said stator comprising upper and lower discoidal portions lying closely adjacent the upper and lower surfaces of the rotor and including upper and lower central openings for ingress of material to be dispersed, said stator having an annular portion extending between the upper and lower discoidal portions and about the rotor, said rotor having outwardly projecting blades disposed to trail relative to the direction of rotation and proportioned to terminate in relatively close juxtaposition to the inner periphery of the annular portion of the stator, said rotor blades being arranged to face both of said central ingress openings to receive material entering from the upper and lower sides of said dispersion means, said annular portion having a circumferential series of substantially radially extending vertical slots of relatively narrow width as compared with their outward extent.

References Cited in the file of this patent UNITED STATES PATENTS 1,393,632 Mitchell Oct. 11, 1921 1,540,853 Macfie June 9, 1925 1,794,214 Thurm et al. Feb. 24, 1931 1,819,118 Preleuthner Apr. 18, 1931 2,169,339 Ditto Aug. 15, 1939 2,390,898 Rechtin et a1. Dec. 11, 1945 

